Whether it's a stool or a chair, you generally need 24" per adult to have comfortable seating. You can do a banquet at an inch or two less because people expect to be squished. If you have larger individuals, you need a little more. You have a little leeway on stools because the knees angel down instead of out. And while 24" is good as a standard, Americans tend to value personal space, and 27" is nicer for general family seating rather than formal dining.

Suggestion: It doesn't really add seating, but if you expect to have family meals at the island, even if it's just breakfast, if you can pull out your overhang some, you could put two stools on the sides so that people could see each other. People don't really like being seated all in a row. You should be able to use four stools in that configuration and recapture the area of the posts.

I am thinking of doing 3 for our 96" long peninsula. I just think 4 will feel tight.

We have 4 stools now with 92" from inside post to inside post and it's no problem for us.

You should definitely get 4 stools made while you have the chance. You can always store one in the basement if you prefer the extra room for day-to-day use, but you'd regret not having it available for larger gatherings. Pulling out a non-matching stool when you have company isn't a great solution, as I learned from experience. :(

In our last home we had 3 stools at first and then when we wanted to add a fourth a couple of years later for occasional guest seating, the original stools had been discontinued. The resulting non-matching but "close" stool always bugged me.

With posts like you have, seating is less flexible. People cannot slip in/out on the end seats b/c the posts are in the way. This means you really should have at least 96" of clear space for 4 seats...more would be better b/c of the posts. "Clear space" means the open space b/w the posts, not counting the posts themselves. I suppose 95" would work for 4...but since the stools you have chosen do not swivel, more room may be needed since the posts are going to inhibit movement.

I second Plllog's comment about having seats on the ends so you are not all "sitting like ducks in a row" or like "ducks in a shooting gallery"! Meals mean conversation, and conversation means facing each other.

I just looked at the stools you want, I may be wrong but the 18 inch measurement looks like the seat. Have you double checked? Also is there a slight flare to the legs?

Buehl and Eandhl have good points. You do need more than 6" between to get in and out, and if your base is bigger than 18" you don't even have that.

If you can add enough room for seating on the sides, you can always line up the stools to have them out of your way while you're just walking to and fro, and bring one or two to the side when people are sitting down.

Thank you for all the feedback. Unfortunately the island is being installed as we speak so I can't change it at this point. I honestly never even thought about the bottoms being wider than the seats (they definitely are). I think I may just order four and have one as a back up as taggie noted.

Thanks again

If its any help to you, my island is 110 inches long but the opening for our stools is only 69 inches wide. It accommodates my three stools very comfortably. They have 18 inch seats but the backs are actually wider than that by a couple of inches. I would think the extra 25 inches you will have would be adequate for a fourth stool. Three might even look too sparse.

I think I would go for 4 stools, mainly so you have them and I think they will fit. How often are you going to have 4 people sitting at the island? Are you a family of 4 who will be eating their meals there? We have 4 in our family but it is rare that we are all home to eat at the peninsula.

I also think I would add some overhang on one end of the island. We have a peninsula that is 8 ft long (no support posts though) but when we eat or have company and are hanging out at the peninsula, we always end up pulling a chair/stool up on the short end... it makes for easier conversation. The one mistake I made was only allowing a 6" overhang on the short end. We still use it but a deeper overhand would have been more comfortable. Just something to consider.

Good point, mercymygft. I forgot to mention that we have a 14 inch overhang on the end of our island just for that reason.We keep a backless stool slipped underneath for when we need the extra seating. I do find that often times my stools are used by whomever happens to be keeping me company while I'm in working in the kitchen. In those cases, stools all in a row are not an issue.